Patent attributes
An internal gear 10 is rotatably received within a housing 8 (planetary carrier 2 and case 4), and a sun gear 12 is rotatably disposed on a circle located inside of and concentric with the internal gear 10. Planet gears 14 which are carried within carrying openings 2c formed in a planetary carrier 2 are disposed between the internal gear 10 and the sun gear 12 in meshing engagement with the internal gear 10 and the sun gear 12. The internal gear 10, the sun gear 12 and the planet gears 14 each have spherical gear teeth, and develops a thrust upon occurrence of a relative rotation therebetween. A coupling 16 is connected to the inner periphery of the internal gear 10 through helical splines 10d and 16a for purpose of power transmission. The helical splines provide a novel thrust generating mechanism, which enlarges the extent in which a bias ratio can be adjusted.
